The Chinese government is sponsoring cyber-espionage to attack top U.S. companies, according to Grady Summers, vice president of security firm Mandiant.

Virginia-based Mandiant published a 60-page report detailing allegations over a six-year period against a group of hackers -- known as Comment Crew -- which Summers linked to a secret division of the Chinese military.

Summers told CNN: "China is attacking the U.S. on a scale like we've never seen before... We believe that the Communist Party of China is very aware of this."